There have been numerous tree stands which have been patented and/or marketed for use by hunters and sportsmen. Two successful "sit and climb" tree stands are produced by Amacker, Inc. and are disclosed in U.S. Pat. Nos. 4,316,526 and 4,331,216. The Amacker tree stands, while commercially successful, still leave something to be desired in certain respects. The most important of these is that the Amacker stands damage the trees on which they are used by engaging the tree with spikes or studs, designated by the numerals 6, 7, 18 and 19 in the aforesaid patents. These spikes pierce the bark of the tree and can lead to the spread of disease from tree to tree. Accordingly, in certain wildlife management, stands which use spikes are forbidden. A second drawback is that as a climber ascends the tree the diameter of the tree diminishes. Accordingly, the angle of inclination of the sit and climb tree stand changes relative to the tree. Commonly, the climber will estimate the amount of change at the base of the tree and attempt to apply a correction in the initial phase of the climb so that as he reaches his desired height the change in inclination positions the tree stand in a level orientation.
This is seldom fully successful. Amacker in U.S. Pat. No. 4,316,526 indicated some adjustment of the angle could be achieved by loosening and retightening a pair of wing nuts when the hunter was at the desired elevation. It would appear that loosening of the tree stand's connective members while in a tree could, in some instances, lead to undesirable results.
U.S. Pat. No. 4,230,203 to Sweat also discloses a sit and climb stand; however, Sweat also uses back blades which cut into the tree on the side thereof opposite the platform and a front brace which cuts into the front of the tree. The Sweat Platform is connected to the back bar laterally of the engagement of the back bar with the tree; thus if the occupant's weight shifts laterally of the centerline of the platform, the platform has a tendency to tilt and throw the occupant from the stand.
PCT/US79/00800 filed by Fonte, disclosed a pole climbing apparatus which uses a set of pole engaging blades mounted between the legs of a V-shaped or U-shaped back bar. Although this device appears useful for climbing poles of uniform sizes, it also appears to engage the poles substantially at the front and rear in the same manner as Sweat and would clearly be unstable if used on a tree of variable diameter since the described blades are not capable of automatically sizing themselves to the tree diameter, most trees change in diameter with height.